1. Field of the Invention
The present invention relates to a glass run for attachment to an inner periphery of a door frame of a motor vehicle for guiding a door glass as it is raised and lowered.
2. Description of Related Art
As shown in FIG. 1, a glass run 10 is attached to an inner periphery of a door frame 12 of a vehicle door 14 for guiding a door glass 16 which is raised and lowered. FIG. 2 is a cross-sectional view taken along the line 2-2 of FIG. 1, and shows a conventional attaching structure of the glass run 10.
As shown in FIGS. 1 and 2, conventionally, the glass run 10 is fitted in a channel 40 formed in the door frame 12 to guide the door glass 16 upwardly and downwardly, and provide a seal between the door glass 16 and the door frame 12. The glass run 10 is formed by connecting extruded straight parts 18 adapted to be attached along an upper side, a front vertical side and a rear vertical side of the door 14, with corner parts 20, each being formed by molding in conformity with a corner of the door frame 12.
A door weather strip 22 is attached to an outer periphery of the door frame 12, and an opening trim weather strip 24 is attached to a flange provided in a door opening portion of a vehicle body, thereby sealing between the vehicle door 14 and the vehicle body.
As shown in FIG. 2, the glass run 10 includes an outer side wall 26, an inner side wall 28 and a bottom wall 30, and has a generally U-shaped cross-section. An outer seal lip 32 and an inner seal lip 34 respectively extend from open ends of the outer side wall 26 and the inner side wall 28 towards an interior of the glass run 10. And an outer cover lip 36 and an inner cover lip 38 respectively extend from open ends of the outer side wall 26 and the inner side wall 28 towards the bottom wall 30 along exterior surfaces of the outer side wall 26 and the inner side wall 28.
The glass run 10 is attached to the door frame 12 by inserting the outer side wall 26, the inner side wall 28 and the bottom wall 30 in the channel 40 such that the outer cover lip 36 covers a lower end of an outer body panel 42 and the inner cover lip 38 covers a lower end of an inner body panel 44.
When the door glass 16 enters an interior of the glass run 10, an outer periphery of the door glass 16 is sealed and held with the outer seal lip 32 and the inner seal lip 34.
When the door glass 16 is raised to a closed position, an upper end of the door glass 16 pushes the bottom wall 30 of the glass run 10 upwardly. At this time, the bottom wall 30 does not absorb the upward movement of the door glass 16 completely so that the upper end of the door glass 16 pushes the channel 40 via the bottom wall 30 to cause occurrence of noises which degrade driving comfort. When the upper end of the door glass 16 pushes the bottom wall 30, the bottom wall 30 deforms to shift the upper end of the door glass 16 from a prescribed closing position so that the seal lips 32 and 34 may be undesirably deformed to lower the sealing properties.
Accordingly, in order to absorb the upward movement of the door glass, a tubular part has been provided in the bottom wall, or a sponge member has been attached to the bottom wall (see Publication of unexamined patent application No. Hei 8-318740 and Publication of unexamined utility model application No. Sho 62-413, for example). In order to provide a tubular part 46 in the bottom wall 30, as shown in FIG. 3, the hollow extruding method is normally adopted, but in order to keep atmospheric pressure in the tubular part 46 during extrusion, a high level pressure control is needed. Therefore, it is difficult to hold the configuration of the tubular part 46, and it is also difficult to increase the rate of extrusion, whereby preferable productivity is not effected. Where a sponge member is attached to the bottom wall, the sponge member with a great thickness cannot be provided in a narrow space between the bottom wall and the door frame, whereby a sufficient shock absorbing force is not effected. On the other hand, if the sponge member is made thick to increase its shock absorbing force, the stability of the bottom wall relative to the door frame may be degraded.
There has been also proposed to provide a lip in the inner side wall adjacently to the bottom wall for contacting the upper end of the door glass, and absorbing the shock caused by the pushing of the upper end of the door glass (see Publication of examined utility model application No. Hei2-15694, for example) In this case, however, the lip does not exhibit sufficiently high elasticity so that a sufficiently strong shock absorbing force cannot be effected. In addition, where this lip has been used for a long period, it has been repeatedly pushed by the door glass to cause permanent deformation, whereby the shock absorbing effect may be lowered.
There has been also proposed to gradually increase the wall thickness of the bottom wall outwardly for enabling the bottom wall to readily flex and absorb shock caused by the pushing of the upper end of the door glass (see Utility model No. 2578541, for example) In this case, however, the shock caused byte pushing of the door glass cannot be sufficiently absorbed with the flexion of the bottom wall, and it is difficult to obtain a large space enough for the thick bottom wall between the bottom wall and the door frame. Consequently, a sufficiently strong shock absorbing force cannot be effected.